Welcome to the Program
by OCfan11
Summary: Things absolutely do not follow the script, and it all starts with there being twins.
1. Pre-Prologue

Pre-Prologue

"Hi there, stranger!" Byleth looks up at the familiar voice. The fighting instructor of the Officer's Academy leans against the gate. "Long time no see!"

Byleth smiles, stopping in place and spreading out his arms. "Come greet your big brother!"

To the students' shock, their strictest teacher runs from the gate and then flying tackles him. Many eyes widen when she _laughs_ as he spins her around.

"I'm older," the female twin mutters as he sets her on the ground. Their hug is a desperate, familiar thing reminding them _they aren't alone_. They separate with a wide grin and eyes too sharp. Then she stops ignoring the others, greeting everyone who's come with Byleth.

_At least she knows what's coming_, he thinks, watching with a fond smile as her emotions are placed behind the cool mask she carries from last life. _We'll get through this._

What he gets from his last life is the ease to make friends. With his sister laying the groundwork all these years, it's no wonder he's going to be offered to teach.

He is the most approachable twin, after all.

* * *

**Disclaimer: I do not own Fire Emblem. All rights belong to their respective owners. **

**A/N: No idea how this is going to go.**

**Thanks for reading! I hope everyone has a fantastic day**


	2. Prologue

Prologue

Time is a social concept. What time travel really means is control over movement. Location is the points in space, in the overarching universe. Time moving forward means the world keeps rotating, the galaxy keeps turning, and universe keeps expanding. To rewind time means not just rewinding the moment, but to force the universe to collapse backwards before pushing it away again.

Some could claim that this is the power belonging to greatest being in the universe: The Beginning.

In a universe of magic and mayhem, the inhabitants of a continent called Fódlan call her Sothis. They have been fooled, and in time she has fooled herself. Sothsis is not The Beginning, but a Beginning. She can control the flow of a concept, not the movement of the universe. Sothis has many powers to claim; restarting the overarching universe is not one of them. She paused time once in her desire to make the perfect vessel, and the universe froze though the things inside of it kept moving. There are consequences to a stationary universe. Eventually, the walls begin to rub away.

Sothis fades long before this. Her time halting powers and healing the land take a large toll on her spirit, causing her to fall into a long sleep. All she leaves behind is a stone and an empty body, knowing one day she will wake and walk the world once more.

Her last child, having no idea, picks the stone from the vile Sword of the Creator and begins to shape the continent into something her mother can rule. She spends long years attempting to shed her hatred for humanity with little success; this is why she cannot rule more than a continent. Her attempts to obtain Heroes Relics – things made by bones and hearts of _a Beginning_'s slain people – are unsuccessful. The world's eyes pass over her, never truly realizing their archbishop never ages nor changes beyond the name. As the world continues to rotate, those which killed Sothis find ways to reach immortality with Crest Stones, becoming Those Who Slither in the Dark.

Lady Rhea – the archbishop – falls in love with a mortal man who saved her life and rewards him with longevity and her Crest without his knowledge. One hundred years later, Sothis' last child begins experimenting to revive her mother the same way Those Who Slither in the Dark keep returning. She implants the stone her mother left behind into those she deems worthy, whether they will be missed or not.

Number twelve is slated to be the blue haired political captive of the church. Unfortunately, life never goes as expected. The man Lady Rhea gave extra life to finds the blue haired maiden and the two fall in love. Without knowing it, he stops Rhea from completing the experiment.

The man's name is Jeralt.

He isn't there when Rhea gives the ultimatum: _I finish the rituals and implant it on your child, or I place it in you_.

He isn't there when the birth happens, and no one realizes what it means when the ritual calls for an old soul.

By the time of the child's conception, the walls are already paper thin.

l-l-t-l-l

Here is a Truth: there are many ways Fódlan's universe attempts to right itself. Infinite ways. Sometimes, the child is a boy. Some gaps in the multiverse have girls. There are few times where Rhea tells the truth and the child is stillborn, and this is where Sothis wakes up and takes over, the blue haired captive alive just long enough to see her child breathe.

In very few, the child never makes.

In almost all, the conception results in the formation of _twins_.

Fódlan is a war-torn land, with many old souls clinging to the plane. If close enough, it is easy to ground an old soul to a body. Here, Sothis is to consume the soul of it and the host to allow her heart to merge. Then, she takes over. Not having a second, aged soul causes too much strain on the body it merges too. Those Who Slither in the Dark have a way of finding the reincarnates. Rhea does not.

With the metaphysical walls protecting Fódlan from other universes so thin, it is easy enough to ground a soul with a slight of hand. Fódlan is always touching other universes, and their insides all turn at different speeds. The difficulty, and why there is only ever one birth, is finding dual souls for the twin bodies. Everyone in Fódlan exists once, and any reincarnates can be considered _time travel_ if the soul wakes in their previous body. Having at least two different universes synced up, where the two souls – identical in makeup – brush Fódlan's Universe at the same time _in the same space, _is a one in infinity's chance of happening. One child will be destroyed by the next ritual if there is no reincarnated soul protecting it.

One boy or one girl. In the universes where the soul came from Fódlan, Sothis takes control. In the reincarnation from other universes, it depends on the mother's sacrifice.

One in infinity is still possible.

Let's say there are two people.

They exist in the same location, taking up the same amount of space.

Their nature and nurture were different all their lives.

They have never met, and yet know the other intrinsically.

Right down to the level unexplainable by science.

What happens when the will of two is in perfect sync?

In this case, _twins_.

l-l- -l-l

Here is the end.

A man and a woman are dead, gone in their sleep where they couldn't protest the slight of hand.

Here is the beginning.

A girl is born with rasping breathes and struggling to cry.

A boy is born five minutes later, screaming as loud as he can.

Here is the middle.

Within those five minutes, a blue haired woman who only has memories of the monastery begs the archbishop to save her daughter. _Do whatever to me, just don't hurt my daughter!_

The woman is still having contractions, Lady Rhea must still play nursemaid. She asks, _are you sure_, because she has practically raised this woman as her own and doesn't want to lose her. This weak, docile human who's never been allowed out of the monastery. _There are two children._

The prisoner tells the false God, _don't hurt my babies!_

This is an end.

A blue haired woman sees her son crying and cries herself. She watches him get put to the side, on less fancy blankets than the girl in a ritual star. She tries to sit up and away as Lady Rhea smiles sweetly and tells her, _I'm sorry_.

The human woman is dead; one unwilling soul for Sothis.

This is the beginning.

Two babies look into each other's eyes and bond instantly. He is telepathic and she is an open connection. They are each other and see two lives pass before their eyes faster than either can compute. They are in this together.

Try to reach for each other as he screams, and she records.

This is the middle.

Lady Rhea – the _Immaculate One_ – finishes the ritual and shoves her mother's heart into the chest of the girl. She crows in victory as tattoos begin to ink on the babe's leg, a painful burning that has the girl cry once and fall silent, turned away from her brother.

She calls this child _Sothis_ and _mother_, not noticing the tattoos stop and fade slightly, not noticing the tattoos on the boy's back come into being while she cries with happiness. The archbishop believes she has done it.

This is the end.

The will of two in perfect sync beats the will of one. Sothis is a Beginning with only half the time and creation powers she thought she had. Either child would have been a perfect vessel, but together they outmatch her. Inside the female's heart, the Crest Stone shatters and activates the Crest of the Goddess in the children's shared blood.

The Goddess Sothis is dead, and no one knows to mourn.

This is the story.

A single father named Jeralt names his eldest Avatar and youngest Byleth. Avatar does not cry, and Byleth is too strong. He overhears the archbishop call his daughter the Goddess' name, notices both children are fearful of her, and fakes the children's death so he can protect them.

Fódlan rights itself and for the first time the walls between universes mend. A girl knows too much and a boy is too strong. A man stays away from drinking only for his children. An archbishop despairs in her monastery, and Those Who Slither in the Dark smell blood in the water.

Meanwhile, a few old things are beginning to wake up...

* * *

**A/N: I've finished Edelgard's route and am mid-way through the Church route, so I thought I had enough info to at least do the prologue. Rating is getting bumped up to M because this game is dark. **

**Thanks for reading! A really big thank you to MiserableSOUL660, and Abbi for reviewing! The support really means a lot!**

**Thank you to everyone who is reading this story! I hope you have a fantastic day**


	3. In the Beginning – Part One

In the Beginning – Part One

Jeralt Eisner used to be a man who did good for the sake of being good.

"No, Avatar. You can't have solid foods until your stronger."

That was before he stopped aging. Before he worked for the Knights of Serios.

"Byleth, it's wrong to take your sister's food."

He's two years sober, a week fleeing from the church, and in over his head.

"You two-" he sighs. It's probably the most adorable thing they do; Avatar grasping her brother's leg with all her strength and him crawling along, dragging her across the floorboards. "You know what, carry on."

He's scared and yearns for a drink more than ever. The children are so opposite of each other it makes him twitchy. Avatar clings only to her father or brother and ends up curling up into a ball to shake if left alone. Byleth is too curious and hates being picked up, hides away every chance he can and giggles when he's found. Byleth cries when they're both hungry, Avatar is always the first to sleep.

They both look three months old instead of three weeks old.

Jeralt's hands shake as he prepares the inn's bedding in a way they won't fall off. The doctor had said his son's heartbeat was a smidge fast, his daughter's low. He claimed it wasn't uncommon to see one healthier twin, but Avatar's inability to roll was concerning. That she doesn't cry might mean a problem with her lungs. The biggest worry was Byleth accidently hurting her.

It doesn't seem as large an issue now, not with how in sync they are. Byleth doesn't tug on his sister, going still until she's holding him. He babbles loudly and listens when she softly babbles back, not that they make noises often. The silence only makes his fears worse. Like now, he can't hear his daughter getting dragged on the floor.

Jeralt turns, and then breathes a sigh of relief. Avatar's lower half can be seen under the windows. The man pulls back the curtains, his son giggles at being found. Avatar releases her brother to open and close fists at her father. The man kneels and snags them both, "Time for bed, kiddos."

Avatar falls asleep on his shoulder. Byleth wiggles and whines until he's put under the covers. A pillow separates the kids, and his son looks up just to make sure she's still here. More wiggling, Jeralt sits on the edge and lets his kid try to gum at his hand while he tells a story. Only when Byleth is asleep does the too old, young looking man break a bit more. "What am I supposed to do?"

The children are growing too quickly, and he isn't aging. The plan had been to get as far from the monastery as possible, maybe get hired as some small town's boarder guard to give the kids a bit of stability. Like this, he's not sure they can settle anywhere. He'll have to take odd jobs to support them. Jeralt can take down monsters by himself, but they can't risk the attention. He can't risk losing time with them.

_If they're aging quickly, how long-_

No, he refuses to think about it. He'll teach them the best he can. Language, reading, writing, spells, glyphs, self-defence- he really should be writing this down. What will they need to learn? What can he teach?

"I wish you were here," Jeralt bows his head and prays his wife is in a better place. "I never wanted to do this without you."

He cries and continues to mourn.

Jeralt still doesn't turn to alcohol.

l-l-l-l-l

They rest on the steps, a throne behind them and the world turning below.

"So, let me get this straight," Byleth is a man here, tattoos still on his back but he looks like his _before_ self. "There are three houses."

"Correct," Avatar traces the markings on her legs. She looks like her _before_ self as well, though her hair flickers blue on occasion.

"And you have to pick one."

"Mhm."

"And you're actually a teacher, not some master strategist."

"Bingo."

He falls silent for a moment. "What do you think the pitch meeting for that game was like?"

Finally, she cracks a smile. Lowers her voice. "Okay. So we do the Fates thing, but- and hear me out -school teacher."

"Fates?"

"Fire Emblem: Fates."

"Never heard of it."

"Ugh," she goes back to a blank face. "Our worlds were so different."

"I mean, at least you know what's going to happen?"

"War," she flicks her skin. The world below them keeps turning.

"That's a given if it's a Fire Emblem game."

"The Fire Emblem isn't even in it."

"Wait, really?" Byleth blinks owlishly at her.

"Yah. There are these things called Crests, but no physical emblem or thing we need to collect. It's rather disappointing."

A silence. "Maybe we can find it? Just because it's not on the continent doesn't mean it's not on the planet."

"And what would we do with it?"

"Well… um… show it off?"

Avatar snorts, smiles. "Okay, so, what was the Fire Emblem in your world?"

"Ughhh, it was called the Crest of Flames," Avatar freezes while Byleth thinks about it, "and the Binding Shield. There were five gems. It could open any treasure chest and repel dragons."

"Okay," Avatar nods slowly, an idea coming to mind. "Well, there are people in this world with the Crest of Flames. Maybe they'll know something about it. Is the Fire Emblem cursed in your lore?"

He gasps. "Is it cursed in yours?!"

"Um, yah?"

"Then maybe we shouldn't," Byleth groans and reclines on the steps. "This place is a nightmare."

_This place_ is their shared headspace, only accessible when they are both asleep. More dream than nightmare. "Well, it's something to think on." Avatar reclines as well, crossing her legs and waving her fingers to zoom out. The expanding universe unfolds before them. "We've got years before the plot starts. Let's work on balancing our stats first."

He makes a face. "Any luck with the strength stat?"

She glares at the pun. He laughs.

Byleth points out, "At least we aren't going to be children forever."

She concedes the point.

l-l-l-l-l

Their father exercises with them in the form of games. He'll put Byleth on either side of Avatar and have her roll or crawl towards them. Both father and son loudly cheer her on. For Byleth, they have a little competition where the boy has to throw balls at small target-like drawings on the ground. Byleth has terrible accuracy, but that isn't the point. It's to regulate his strength, just as Avatar needs to work on hers. When Jeralt sits her up – they're still working on her core – she can roll the ball to a target within a few feet away. It's a perfect roll every time. Byleth can throw the ball across the room without a good grip. Jeralt is slowly coming to realize what they already know.

The twins are perfect splits of each other.

What he can't understand is the effects of their Crest, thought to be fair he doesn't even know they have one. As the essence of _a Beginning_ resides in them, the Crest of the Goddess – more commonly known as the Crest of Flames – comes with more than the usual healing ability. They are input and output. Receiver and sender. Knowledge and Power. Avatar constantly sees the world as numbers and words, while Byleth is a bundle of force. He has a presence that makes people sit up and take notice, while her emotions have been muted since the chest implant; _and she remembers everything since her rebirth_.

What Jeralt doesn't know, is that his oldest is teaching his youngest the language spoken commonly in Fódlan. He doesn't realize that the siblings telepathically speak to each other whenever Avatar isn't overwhelmed by the information of the world. Doesn't pick up on Byleth hardly touching anything with his fingers as he learns the range of his strength. What the father does is talk to them, play with them, and never shy away from them. Not at their quirks, or at their start to a speedy aging.

What he does notice is the intelligent gleam in their eyes and their love of his stories. If he can connect with them this way, he'll talk for hours. Anything to keep them engaged and not causing trouble. A month on the run passes, and he's finally comfortable enough to leave them in a village while he hunts to earn a bit of money.

When he comes back, picking them up from the woman who coos over how sweet they were, Byleth is fast asleep and Avatar stirs for just a moment. Just long enough to utter her first word, "Daddy."

_This_, Jeralt realizes with misting eyes and a smile, _is why he does it_. These are his children, no matter what.

Quietly, his fears begin to ebb away.

l-l-l-l-l

His name is Cichol, and he groggily wakes to the smiling face of Seiros above him. "Sister."

"Brother," she hums, cupping his face. "I have missed you so."

The last of his memories are stains on his soul, and his strength is not yet complete. "Seiros, why am I awake?" Where is- "Cethleann! Where is she?!"

"Calm yourself, dear brother," Seiros hums and continues to stroke him. The touch feels… different. "She is in the next room, as she was when you fell into slumber. Do not fear. Your daughter is safe."

Panic gone, the toll is sleep dragging at him again. "Seiros, I-"

"Hush, brother," she holds a finger to his lips. "You have been asleep for a long time. Rest. I will watch over you both and explain everything when you two are reunited."

He sighs, eyes forcibly shutting. "Thank you."

Lady Rhea removes herself from his side, smile breaking as tears threaten to spill. She giggles and cuts a path to the next room, strengthening the silencing glyphs as she goes. It would not bode well for Cichol or her guards to hear what's to come.

The young girl – a sister to the body in the other room – thrashes on the ritual star she is bound to. The knights believe Lady Rhea is conversing with an old, hermit friend. That he's the one who gives her Crest Stones, and not that she scavenges rubble looking for her sleeping brethren. They don't know she's trapped a few of the squatters who took refuge in Zanado. They'll easily buy that she convinced her friends to come to the church, where their skills can be put to use. In a way, she is doing just that.

The Immaculate One plucks the Crest Stone from the bones in the room. She coos at it while the girl screams around her gag. "Cethleann… darling Cethleann…"

Minutes later, the screams go quiet. The change is instantaneous. Head hair volumizes and curls a light green. The tan and sickly complexation revitalizes. Calloused fingers turn soft. Rhea holds one to her chest as green eyes flutter open. "M…"

Lady Rhea's heart fills with joy. Her brother and niece will walk this world once more.

* * *

**A/N: As the family of three runs, Jeralt is left with the looming question: how do you run from a major religion? The children are not children. Two Crest Stones have awakened.**

**Thanks for reading! A really big thank you to ShadowWolf223, TheUzigunner, Baelor77, Sergeant Daniel, and Rileyty for reviewing! The support really means a lot!**

**Thank you to everyone who is reading this story! I hope you have a fantastic day**


End file.
